This invention relates to systems and methods in which the dynamic conditions attendant a vehicle crash are simulated in order to evaluate cabin design and vehicle safety systems, such as occupant restraint devices. More specifically, the present invention relates to non-destructive crash tests that include the simulation of vehicle pitch (crash-related fore and aft vehicle rotation).
To evaluate vehicle crash worthiness and occupant safety, vehicle manufacturers and regulatory agencies conduct full-scale crash tests in which a vehicle is caused to collide with an obstacle in a manner that duplicates a real world collision. Sensors, located on the vehicle and/or crash test dummies that are placed in the vehicle, provide data that is recorded for analysis and evaluation.
Full-scale crash testing is expensive because it destroys the test vehicle, which in some cases is an expensive prototype or an early stage production unit of limited availability. The expense and the possible lack of additional test vehicles limit the amount of full-scale crash tests that can be conducted, thereby impeding necessary analyses, including the design, development, and ongoing product testing of vehicle safety systems, such as occupant restraint systems and the design of vehicle interiors from the standpoint of occupant safety.
The need for less expensive and readily available crash tests has led to the development of non-destructive crash test arrangements in which vehicle deceleration is recorded during a full-scale crash test. This deceleration data, which is often referred to as a crash pulse, is used to control either the deceleration or acceleration of a crash sled in a manner that substantially matches the crash pulse. In such an arrangement, all or a portion of the occupant compartment of the vehicle, often referred to as a vehicle buck, is mounted on the upper surface of the crash sled. Instrumented crash test dummies occupy the vehicle buck during the deceleration or acceleration of the test buck. The instrumented dummies provide data that can be evaluated to indicate the kind and degree of occupant injury that might result from the simulated crash and/or be evaluated to determine compliance with crash safety limitations pertaining to occupant head and chest acceleration and various loads and forces that can be experienced by a human occupant during a crash event.
Current crash sled systems provide relatively accurate results with respect to replicating crash event acceleration along an axial direction that corresponds to the vehicle travel path at the time of a crash. However, most systems cannot simulate dynamic conditions, such as vehicle pitch, that can occur during a crash. Vehicle pitch occurs, for example, in frontal and rear impact crashes in which the front of the vehicle is often abruptly thrust downwardly and the rear of the vehicle is thrust upwardly. The accelerations associated with this downward and upward motion can be significant enough to cause or contribute to occupant injury.
The prior art includes various attempts to provide a crash sled system that replicates both vehicle pitching motion and the axial (substantially horizontal) deceleration that is experienced during an actual crash event. One such attempt is disclosed in U.S. Patent Application Publication No. 2010/0288013, which discloses a conventionally configured crash sled having an auxiliary platform that is located above the crash sled upper surface. A support member, hinged to the crash sled and the auxiliary platform, permits positioning of the auxiliary platform above the crash sled upper surface and permits tilting (pitching) of the auxiliary platform relative to the crash test surface. Elevation of the forward and rear ends of the auxiliary platform is controlled by hydraulic or pneumatic actuators that are mounted on the crash sled and include extendable actuator rods that are mechanically linked to the auxiliary platform front and rear ends. In operation, pressure is established in the actuators that is sufficient to rapidly upwardly accelerate the ends of the auxiliary platform. A braking system interacts with the extendable actuator rods to control movement of the front and rear ends of the auxiliary platform so that the pitching motion of the auxiliary platform replicates the vehicle pitching experienced during an actual crash.
U.S. Patent Application Publication No. 2004/0230934 also discloses crash sled arrangements that include simulation of vehicle pitch that is incident to a vehicle crash. U.S. Patent Application Publication No. 2004/0230934 discloses arrangements similar to the crash sled of U.S. Patent Application Publication No. 2010/0288013 in that an auxiliary platform that is located above the crash sled and actuators for controlling the pitch of the auxiliary platform are located “on-board” the crash sled. The primary differences between the arrangement of U.S. Patent Application Publication Nos. 2010/0288013 and 2004/0230394 are the nature of the actuators that control pitch of the auxiliary platform and the manner in which the actuators operate. More specifically, in U.S. Patent Application Publication No. 2004/0230394, the actuators extend in the vertical direction from the upper surface of the crash sled and the front and rear ends of the auxiliary platform. In operation, the actuators are independently controlled with auxiliary platform pitch determined by the difference between the vertical forces being asserted by the actuators.
German Patent Application No. 10118682 also discloses a pitch simulation arrangement that includes an auxiliary platform mounted for movement with a conventional crash sled. German Patent Application No. 10118682 differs from the noted U.S. Patent Application Publications in that the actuators that control movement (pitching) of the auxiliary platform are not located on the crash sled. Instead, the actuators are mounted between the floor or foundation on which the crash sled rests and guidance rails that extend along each side of the crash sled. During the simulation, the forward and aft ends of the auxiliary platform are engaged with the guidance rails and the actuators are dynamically driven to control pitching of the auxiliary platform.